In general, a relay driver is a circuit that operates a relay so that the relay can function appropriately in a second circuit. For example, the relay based on relay driver operations can be a switch in the second circuit. A problem exists where contemporary vacuum relays do not have a needed standoff voltage from contact to chassis or coil. Thus, any breakdown to a case of the contemporary vacuum relays can arc to coil contacts due to a small clearance distance. In turn, an isolated case and an isolation power supply are utilized because any internal voltage breakdown will not affect or damage extra-low voltage (ELV, which protects against electrical shocks) circuits or put a user in jeopardy.
The contemporary high voltage relays use large open frame high voltage contacts to isolate voltages and switch high voltage outputs. These contactors require a large amount of voltage and power (e.g., 115 Vac or 220 Vac) to drive them. The contactors are also susceptible to oxidation or arcing to nearby objects, along with being affected by altitude and humidity.